A DFT study on the formation of CH3O on Cu2O(1 1 1) surface by CH3OH decomposition in the absence or presence of oxygen

Abstract

The formation mechanism of CH3O by the adsorption and decomposition of CH3OH on clean and oxygen-precovered Cu2O(111) surface has been investigated with density functional theory method together with the periodic slab models. Two possible formation pathways of CH3O by CH3OH decomposition on oxygen-precovered (Opre) Cu2O(111) surface were proposed and discussed. One is the O–H bond-cleavage of CH3OH with H migration to Opre to form CH3O; the other is the C–O bond-scission of CH3OH with CH3 migration to Opre leading to CH3Opre. The calculated results show that the O–H bond-breaking path has the lowest activation barrier 26.8kJmol−1, the presence of oxygen-precovered on Cu2O(111) surface exhibits a high surface reactivity toward the formation of CH3O by the O–H bond-cleavage of CH3OH, and reduce the activation barrier of O–H bond-cleavage. The C–O bond-breaking path was inhibited by dynamics, suggesting that the O atom of CH3O is not from the oxygen-precovered, but comes from the O of CH3OH. Meanwhile, the calculated results give a clear illustration about the formation mechanism of CH3O in the presence of oxygen and the role of oxygen at the microscopic level.